CVE-2026-44673: libyang Integer Overflow Leads to Heap Corruption
The National Vulnerability Database has detailed CVE-2026-44673, a high-severity integer overflow vulnerability in libyang, a critical library for YANG data modeling. Specifically, the lyb_read_string() function in src/parser_lyb.c is susceptible prior to version SO 5.2.15. This flaw allows a maliciously crafted LYB binary blob to trigger a heap buffer overflow.
Attackers can exploit this by supplying specially designed LYB data to any libyang consumer. This includes common infrastructure components like NETCONF servers or sysrepo instances. The immediate impact is a denial-of-service via application crash, but the potential for heap corruption opens the door to more severe consequences, including arbitrary code execution if an attacker can reliably control memory writes.
Given libyang’s foundational role in network device management and configuration, this vulnerability is not trivial. While no specific affected products are listed by the National Vulnerability Database, any system relying on libyang for YANG data parsing is inherently at risk. Defenders must identify their exposure to libyang and prioritize patching to version SO 5.2.15 to mitigate this threat.
What This Means For You
- If your organization utilizes NETCONF servers, sysrepo, or any application consuming YANG data via libyang, you need to assess your environment for CVE-2026-44673 exposure. Verify that libyang is updated to at least version SO 5.2.15 immediately. This isn't just about crashes; heap corruption can be a stepping stone for sophisticated attackers to achieve remote code execution.
Related ATT&CK Techniques
🛡️ Detection Rules
2 rules · 6 SIEM formats2 detection rules auto-generated for this incident, mapped to MITRE ATT&CK. Sigma YAML is free — export to any SIEM format via the Intel Bot.
CVE-2026-44673: libyang LYB Heap Corruption via Malicious Blob
title: CVE-2026-44673: libyang LYB Heap Corruption via Malicious Blob
id: scw-2026-05-14-ai-1
status: experimental
level: high
description: |
Detects the execution of libyang-related processes (like NETCONF servers or sysrepo) that are attempting to parse a LYB binary blob using the vulnerable lyb_read_string function. This indicates a potential exploitation attempt of CVE-2026-44673, leading to heap corruption.
author: SCW Feed Engine (AI-generated)
date: 2026-05-14
references:
- https://shimiscyberworld.com/posts/nvd-CVE-2026-44673/
tags:
- attack.execution
- attack.t1204.002
logsource:
category: process_creation
detection:
selection:
Image|contains:
- 'libyang'
ParentImage|contains:
- 'NETCONF'
- 'sysrepo'
CommandLine|contains:
- 'lyb_read_string'
condition: Image AND ParentImage AND CommandLine
falsepositives:
- Legitimate administrative activity
Source: Shimi's Cyber World · License & reuse
Indicators of Compromise
| ID | Type | Indicator |
|---|---|---|
| CVE-2026-44673 | Buffer Overflow | libyang library, versions prior to SO 5.2.15 |
| CVE-2026-44673 | Memory Corruption | libyang library, lyb_read_string() function in src/parser_lyb.c |
| CVE-2026-44673 | DoS | Parsing maliciously crafted LYB binary blob in libyang |
Written by SCW Vulnerability Desk
Source & Attribution
| Source Platform | NVD |
| Channel | National Vulnerability Database |
| Published | May 15, 2026 at 00:16 UTC |
This content was AI-rewritten and enriched by Shimi's Cyber World based on the original source. All intellectual property rights remain with the original author.
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